Overhead hoist



J. L. GRAY OVERHEAD HOIS'I Get. 3, 3967 Filed July 21, 1966 INVENTOR Josue 9h L. way

United States Patent 3,345,039 OVERHEAD HOIST Joseph L. Gray, St. Joseph, Mo., assignor to Gray Manufacturing Company, Inc., Buchanan County, Mo., a corporation of Missouri Filed July 21, 1966, Ser. No. 566,811 10 Claims. (Cl. 254-93) This invention relates to lifting apparatus and, more particularly, to an overhead hoist having novel construction to provide optimum efliciency and simplicity of construction.

It is the primary object of the present invention to provide an overhead hoist operated by a fluid pressure piston and cylinder assembly wherein specialized sealing means is employed to assure more efiicient reciprocation of the piston than has heretofore been possible with conventional seals. More specifically, the sealing structure includes a free-floating annular seal adapted for insertion around a ram connected to the piston, the seal being in intimate contact with the ram and cylinder and shiftable with the ram to maintain substantially complete sealing action.

It is an important object of the instant invention to provide a piston and cylinder assembly utilizing a freefloating seal as above described wherein a spacer is utilized to prevent the seal from closing off the fluid ports of the cylinder during reciprocation of the piston.

Another object of this invention is to provide an overhead hoist of the aforementioned character wherein the ram and piston are suitably bored for complemental fitting and alignment so that a pin connection can readily be made to facilitate economical construction of the assembly and additionally maintain an effective positive connection.

Other objects will become apparent from the following specification and accompanying drawing, wherein:

FIGURE 1 is a fragmentary, front elevational view of an overhead hoist made pursuant to the present invention, showing the same mounted on a frame;

FIG. 2 is a side elevational view thereof, parts being broken away and in section to reveal details of construction;

FIG. 3 is a schematic View showing the valve arrangement of the hoist illustrated in FIGS. 1 and 2;

FIG. 4 is a view similar to FIG. 3, showing an alternate form of valve arrangement; and

FIG. 5 is a cross-sectional view taken along line 55 of FIG. 2.

Referring to FIGS. 1 and 2, the overhead hoist is shown mounted on the lateral bar 12 of a frame 14. Hoist 10 comp-rises a fluid pressure piston and cylinder assembly having an enclosed hollow cylinder 16, a reciprocable piston 18, a ram 20, and valve line mechanism 22. Cylinder 16 presents a transversely circular sidewall 24 having a top plate 26 and a bottom plate 28 at the opposed ends thereof.

Piston 18 comprises a circular plate presenting an upper face 30, a lower face 32, and a cylindrical side surface 34, the latter being adapted for complemental reciprocation along the inner surface 36 of cylinder 16. An axial bore 38 is provided in piston 18 and is intersected by a transverse opening 40 which extends partially through the piston and communicates at one end thereof with side surface 34. An annular groove 42 is formed in side surface 34 and is positioned to intersect transverse opening 40.

Ram 20 is cylindrical in configuration and has an outside diameter equal to the diameter of bore 38 so that it will be complementally received therein. A transverse opening 44 is provided in ram 20 and is aligned with opening 40 of piston 18 for receiving a pin 46 to interconnect piston 18 and ram 20. The particular boring and complemental fitting of piston 18 and ram 20 facilitates connection thereof since it is only necessary to insert pin 46 through groove 42 into the aligned openings 40 and 44. A resilient ring 48 is then snapped into groove 42 to retain pin 46 in its connecting position. Ring 48 also is in intimate contact with inner surface 36 of cylinder 16 to provide a wearing surface between the piston and cylinder.

Ram 20 extends through an aperture 50 provided in bottom plate 28 and terminates at its outer end in a hook-lifting structure 52. A guide 54 having a lower wiper lip 56 is carried by bottom plate 28 and circumscribes ram 20.

An annular, transversely U-shaped seal 58, having a bight 60 and inner and outer depending legs 62 and 64, is journalled on ram 20 with the upper surface of bight 60 normally complementally engaging lower face 32 of piston 18. Seal 18 is dimensioned so that the inner edge thereof presented by inner leg 62 intimately engages ram 20 and the periphery thereof, presented by the outer surface of leg 64, intimately engages the inner cylinder surface 36. Since seal 58 is not directly secured to any part of the assembly, it is slidable with respect to ram 20 and surface 36 to thereby present a free-floating seal between piston 18, ram 20 and cylinder wall 36.

A second transversely U-shaped, annular seal 66 is journalled on ram 20 and the bight 68 thereof complementally engages the inner surface of bottom plate 28. The inner leg 70 of seal 66 intimately engages ram 20 to seal the aperture 50 of bottom plate 28. Seal 66 is identical in construction and configuration to seal 58. A freefloating, annular, channel-shaped spacer element 72 is carried on seal 66 in surrounding relationship to ram 20 and has a larger inside diameter than the outside diameter of ram 20, whereby an annular gap 74 is presented therebetween for receiving the upwardly extending inner leg 70 of seal 66. Piston 18, seals 58 and 66, and spacer 72 are preferably each concentric with ram 20.

A port 76 is formed in cylinder 16 immediately above the upper edge of outer leg 78 of seal 66 and is coupled to the valve line mechanism 22 so that the latter can force fluid into cylinder 16 and withdraw the same therefrom to effect reciprocation of piston 18. Two valve arrangements are schematically illustrated in the drawing, with FIG. 3 corresponding to the hoist shown in FIGS. 1 and 2, and FIG. 4 representing an alternate arrangement also suitable for use with hoist 10.

Referring to FIG. 3, port 76 is in communication with a conduit 80 which leads to a rotatable valve 82 having a T-shaped channel 84, the latter being adapted to selectively connect conduit 80 to a supply tube 86 and an exhaust tube 88. As shown in FIGS. 1 and 2, valve 82 is connected to a swivel bar 90 having pull chains 92 at the opposed ends thereof, each chain 92 being provided with a handgrip 94.

In operation, when it is desired to lift an article carried by hook 52, valve 82 is rotated by a corresponding pull on a handgrip 94 so that channel 84 connects supply tube 86 with conduit 80. A pressurized fluid, either air or liquid, is maintained in supply tube 86 and, therefore, will be directed into conduit 80 and thence through port 76 into cylinder 16 to apply pressure to the lower face 32 of piston 18 to raise the latter and thereby raise hook 52. To lower hook 52, swivel bar 90 is shifted to rotate valve 82 so that channel 84 connects conduit 80 with exhaust tube 88, whereby the fluid between piston 18 and bottom plate 28 is forced from cylinder 16 by action of the weight of piston 18, ram 20, hook 52 and the article carried by hook 52.

As piston 18 is lowered, seal 5-8 is forced downwardly until the lower surface of bight 60 engages the top of spacer 72 which stops the downward shifting of piston 18. In this stopped position, inner leg 62 of seal 58 is received in gap 74 and the outer leg 64 is positioned above port 76, thus preventing the latter from becoming blocked. This provision is important since fluid will be permitted to enter cylinder 16 through port 76 when piston 18 is at its lowermost point of travel.

As piston 18 is reciprocated, seal 58 maintains intimate contact with ram 20 and inner cylinder surface 36 to prevent seepage of fluid past piston 18 and thus efficient utilization of the fluid is assured. If seal 58 does not completely block passage of fluid, ring 48 serves as an additional safeguard to prevent passage of fluid above piston 18. It is particularly noteworthy that the sealing action of the free-floating seal 58 does not interfere with the operation of valve line mechanism 22 for the reason that spacer 72 insures that seal 58 will not block port 76 at any time. For maximum lifting stroke, port 76 should be located near bottom plate 28 so that piston 18 may be lowered as nearly as possible thereto.

The valve mechanism shown in FIG. 4 operates in substantially the same manner as that of FIG. 3, except that exhaust tube 188 communicates with cylinder 116 between piston 118 and top plate 126, there being an orifice 196 in top plate 126 communicating with a second exhaust tube 198. Thus, when valve 182 is rotated to connect exhaust tube 188 with conduit 180, the fluid below piston 118 will be sequentially forced through conduit 180, exhaust tube 188, cylinder 116, orifice 196, and exhaust tube 198. By directing the exhaust into cylinder 116 above piston 118, the exhaust is controlled in such manner that foreign elements such as dust or the like will not be drawn into the cylinder.

Having thus described the invention, what is claimed as new and desired to be secured by Letters Patent is:

1. An overhead hoist comprising:

an enclosed hollow cylinder having! a transversely circular sidewall and opposed end plates;

a piston having a cylindrical side surface adapted for complemental reciprocation within the cylinder;

a cylindrical ram extending through one of said plates and slidable with respect thereto;

lift structure secured to the outer end of said ram;

a port in the cylinder; and

mechanism coupled to the port for forcing fluid into the cylinder and withdrawing the same therefrom to reciprocate the piston,

said piston having an axial bore therein having a diameter equal to the diameter of said ram, the piston having a transverse opening communicating within said side surface and intersecting with said bore,

said ram being received in said bore and having a transverse opening extending therethrough in alignment with the opening in said piston,

there being a pin extending through said aligned openings to connect the piston to the ram whereby when said mechanism is operated to reciprocate the piston, the ram correspondingly reciprocates to shift said lift structure.

2. The invention of claim 1, and an annular groove in said piston side surface intersecting said opening therein, there being a ring seal carried within the groove to retain said pin in said openings and being in intimate contact with the inner surface of said cylinder to effect a seal.

3. An overhead hoist comprising:

an enclosed hollow cylinder having a transversely circular sidewall and opposed end plates;

a piston having opposed end faces and a cylindrical side surface adapted for complemental reciprocation within the cylinder;

a cylindrical ram extending through one of said plates and slidable with respect thereto;

means connecting said piston to the ram for reciprocation therewith;

lift structure secured to the outer end of said ram;

a port in the cylinder between said one plate and the proximal end face of the piston;

mechanism coupled to the port for forcing fluid into the cylinder and withdrawing the same therefrom to reciprocate the piston, and correspondingly shift said ram and lift structure; and

an annular seal presenting an inner edge and on outer periphery, the seal being journalled on said ram and dimensioned so that said edge and periphery respectively intimately engage the outer ram surface and inner sidewall surface, the seal being slidable with respect to said ram and sidewall to present a free floating seal between the piston and said one plate.

4. The invention of claim 3, said seal being transversely U-shaped, the bight thereof normally engaging said proximal piston face, and the inner and outer legs thereof defining said edge and periphery, respectively.

5. The invention of claim 4, said port being disposed adjacent said one plate, there being an element supported by said one plate and positioned to stop shifting of said piston before the latter blocks said port.

6. The invention of claim 5, said element comprising a spacer positioned to engage said seal to stop said piston.

7. The invention of claim 6, said spacer being annular and having a larger inside diameter than the outside diameter of the ram, the spacer being carried on said one plate in surrounding relationship to the ram to present an annular gap therebetween, said inner leg being received in said gap when said piston is shifted toward said end plate, the spacer engaging said bight to stop said piston.

8. The invention of claim 7, there being a second transversely U-shaped, annular seal journalled on the ram, the bight of the second seal engaging the inner surface of said one plate, said spacer being carried on the second seal, the inner leg of the latter extending into said gap.

9. The invention of claim 7, said piston having an axial bore therein having a diameter equal to the diameter of said ram, the piston having a transverse opening communicating with said side surface and intersecting with said bore, said ram being received in said bore and having a transverse opening extending therethrough in alignment with the opening in said piston, said connecting means comprising a pin extending through said aligned openings to connect the piston to the ram.

10. The invention of claim 9, said cylinder having an exhaust orifice opposed to said port with respect to said piston, said mechanism including a conduit coupling said port to the cylinder for communication with said orifice whereby, when said mechanism is operated to withdraw the fluid through said port, the withdrawn fluid will be sequentially directed through said conduit, cylinder and exhaust orifice.

References Cited UNITED STATES PATENTS 1,613,563 1/1927 Grattan 254-93 1,924,477 8/ 1933 Wulf 254-93 X 2,188,364 1/1940 Lannen 254-93 X 2,620,160 12/1952 Ray 254-93 3,146,592 9/1964 Johnson 60-52 OTHELL M. SIMPSON, Primary Examiner, 

1. AN OVERHEAD HOIST COMPRISING: AN ENCLOSED HOLLOW CYLINDER HAVING A TRANSVERSELY CIRCULAR SIDEWALL AND OPPOSED END PLATES; A PISTON HAVING A CYLINDRICAL SIDE SURFACE ADAPTED FOR COMPLEMENTAL RECIPROCATION WITHIN THE CYLINDER; A CYLINDRICAL RAM EXTENDING THROUGH ONE OF SAID PLATES AND SLIDABLE WITH RESPECT THERETO; LIFT STRUCTURE SECURED TO THE OUTER END OF SAID RAM; A PORT IN THE CYLINDER; AND MEACHANISM COUPLED TO THE PORT FOR FORCING FLUID INTO THE CYLINDER AND WITHDRAWING THE SAME THEREFROM TO RECIPROCATE THE PISTON, SAID PISTON HAVING AN AXIAL BORE THEREIN HAVING A DIAMETER EQUAL TO THE DIAMETER OF SAID RAM, THE PISTON HAVING A TRANSVERSE OPENING COMMUNICATING WITHIN SAID SIDE SURFACE AND INTERSECTING WITH SAID BORE, SAID RAM BEING RECEIVED IN SAID BORE AND HAVING A TRANSVERSE OPENING EXTENDING THERETHROUGH IN ALIGNMENT WITH THE OPENING IN SAID PISTON, THERE BEING A PIN EXTENDING THROUGH SAID ALIGNED OPENINGS TO CONNECT THE PISTON TO THE RAM WHEREBY WHEN SAID MECHANISM IS OPERATED TO RECIPROCATE THE PISTON, THE RAM CORRESPONDINGLY RECIPROCATES TO SHIFT SAID LIFT STRUCTURE. 